It is well known in the agricultural arts to apply various treatments to seeds before planting, in an effort to reduce the amount of such treatment that would otherwise be required were it to be applied to a field after planting. For example, treatments may include the application of fertilizers, insecticides, pesticides and fungicides, and normally take the form of liquid chemical that is sprayed onto the seed. While seed treatment apparatuses are commercially available, it is more common to see a farmer spray treatment directly onto seed just before it is drawn up an auger, the auger being employed to mix the treated seed in an effort to spread the treatment coating over as much seed surface as possible before planting. Such manual application, however, normally results in overuse of expensive treatment (due to a failure to properly meter the seed and control the treatment amount) and loss of treatment (particularly due to wind) and may even have health implications depending on the nature and toxicity of the particular treatment being applied, although manual application may also result in too little treatment being applied and therefore a reduction in the desired effect.
Various seed treatment apparatuses have been disclosed in the prior art, some of which have been made commercially available. For example, Canadian Patent No. 518,715 to Calkins provides an early example of a seed treatment device that incorporates metering of seed, where a “dump pan” is employed, but the metering approach is unfortunately inaccurate and the focus of the teaching is on slurry agitation rather than achieving optimal treatment application. Canadian Patent Application No. 2,704,589 to Hunter et al. teaches a more accurate metering system, where seed weight is determined using a load cell to calculate an optimal treatment application, but the apparatus is designed for batch processing in a research setting rather than the high-throughput seed treatment required in a commercial farming operation.
One of the commercially available seed treaters for on-farm use is described in Canadian Patent No. 2,196,001 to Graham. The Graham apparatus, or “G3”, is used with two augers, where one auger transports seed upwardly (from an auger hopper positioned under a hopper-bottom bin or similar) toward the upper intake of the seed treater, and the seed is then sprayed with treatment as it fails downwardly through the seed treater, with the second auger serving to mix the treated seed and transport it upwardly to a truck or storage unit. The seed falls in an annular pattern adjacent the inner surface of the treater, and a centrally-disposed nozzle sprays treatment in a conical spray pattern in an effort to contact as much seed as possible. While this apparatus may provide an improvement over manual application methods, it has been found that treatment builds up around the inner surface of the treater and is therefore wasted. However, a more significant issue has been noted with this and other auger-based treaters, namely, that using an auger to determine volume flow through the system (and hence the amount of treatment to apply) can be quite inaccurate due to product slippage inherent in the screw-type transport mechanism. Also, optimal treatment application rates are provided in mL/100 kg, so a reliance on volume alone without an adjustment for seed density can contribute to an application rate that is not optimized, hence resulting in treatment waste. In a commercial farming operation, the cost of such waste can be substantial.
The problem of treatment waste and optimized application rates in a commercial farming context has not been canvassed to a significant extent in the prior art. One example is U.S. patent application Ser. No. 12/848,412 to Reineccius et al., which teaches an apparatus that provides an accurate means for measuring seed volume to determine an optimal treatment application rate. However, the apparatus itself is of a physical scale that may limit its on-farm application and, while providing a volume determination mechanism superior to that of Graham and other auger-type apparatuses, the teaching does not take seed density into account.
What is needed, therefore, is an apparatus and method that can be applied in commercial farming operations for metering seed to determine a more optimized treatment application rate.